Study of a single line of sight gamma ray diagnostics for measurements of the absolute gamma ray emission from JET

The fusion power produced in a DT thermonuclear reactor is currently determined by measuring the absolute 14 MeV neutron yield of the D(T, α)n fusion reaction. Measurements of 17 MeV gamma rays born from the much less probable D(T, 5He)γ reaction (branching ratio of ∼10−5) have been proposed as an alternative independent method to validate the neutron counting method and also to fulfill the requests of the nuclear regulator for licensing ITER DT operations. However, the development of absolute 17 MeV gamma ray emission measurements entails a number of requirements, such as: (i) knowledge of the 17 MeV gamma ray to 14 MeV neutron emission branching ratio; (ii) the simulation of the gamma ray transport from the extended plasma source to the gamma ray detectors; (iii) a careful determination of the absolute efficiency of previously calibrated gamma ray spectrometers. In this work, we have studied the possibility to infer the global gamma ray emission rate from measurements made with a 3″ × 6″ LaBr3 spectrometer installed at the end of a collimated tangential line of sight at the JET tokamak and using the neutron emission from deuterium plasmas of the most recent experimental campaigns. Results show that 17 MeV gamma ray fluxes at the end of this tangential line of sight have a weak dependence (less than 5%) on the plasma profile and can therefore be used to infer the total emission from the plasma.

Absolute efficiency of a two-stage microchannel plate for electrons in the 30 - 900 eV energy range

We report on an apparatus able to measure the absolute detection efficiency of a detector for electrons in the 30 - 900 eV range. In particular, we discuss the characterisation of a two-stage chevron microchannel plate (MCP). The measurements have been performed in the LASEC laboratory at Roma Tre University, whit a custom-made electron gun. The very good stability of the beam current in the fA range, together with the picoammeter nominal resolution of 0.01 fA, allowed the measurement of the MCP absolute efficiency ε. We found an ε = (0.489±0.003) with no evident energy dependence. We fully characterised the MCP pulse shape distribution, which is quasi-Gaussian with a well visible peak above the noise level. We measured a 68% variation of the average pulse height between 30 and 500 eV. Furthermore, with a deeper analysis of the pulse shape, and in particular of the correlation between pulse height, area and width, we found a method to discriminate single- and multi- electron events occurring within a 10 ns time window.

INVESTIGATING THE CHARACTERISTICS OF LARGE-VOLUME PVT SCINTILLATION DETECTORS IN THE RADIATION PORTAL MONITORS USING MONTE CARLO SIMULATIONS

This paper presents the characteristics determination process of the large-size Polyvinyl Toluene (PVT) scintillation detectors using MCNP5 simulation code. The energy spectra using a 137Cs calibration source, absolute efficiency in the energy range of 50 ÷ 3000 keV, and the angular response of the EJ-200 50×50×5 cm3 and 25×25×5cm3 are investigated. The simulated energy spectra are in good agreement with the experimental spectra. The results of determining the absolute efficiency show that the EJ-200 50×50×5 cm3 and 25×25×5cm3 plastic detectors have detection efficiencies of 16,3% and 9,2%, respectively, at 10cm source-to-detector distance, and down to 0,6% and 0,17% at 100 cm source-to-detector distance. The angular responses of the detectors show that the detection efficiency value reached ≥ 90% of the maximum value with the incident angle less than 5π/6. The results can be applied in the process of design optimization of plastic-based radiation portal monitors.

Spray Coating Luminescence Layers on Glass for Si Solar Cells Efficiency Enhancement

The article presents experimental research focused on the improvement of solar cells efficiency using the photoluminescence down-shifting effect. In the paper, the authors present the results of solar cells performance enhanced with the proposed solution. As light energy converted active materials, rare earth elements of europium and dysprosium were implemented. In the experiments, luminescent layers were deposited on top of photovoltaic protective glass in order to absorb the highest possible amount of ultraviolet light from the incident solar spectrum. Spray coating deposition technology with various types of ink compositions was used for process optimization. It was observed that there are optimal concentrations and solvent types for the best conversion effect and consequently, the improvement of solar cell external quantum efficiency (EQE) together with the PV cell absolute efficiency enhancement.

Does relative (absolute) efficiency affect capital costs?

In this paper, we examine the effect of relative/absolute firm efficiency on weighted average cost of capital (WACC). Using a sample of Korean listed firms, we find that WACC is negatively associated with relative firm efficiency (operational performance) suggesting that firms with higher (lower) relatively efficiency are expected to pay lower (higher) capital costs. When we repeat our analysis using absolute firm efficiency (ROA), we do not find a statistically significant relationship. Our results suggest relative efficiency which is estimated as output (sales) divided by the resources that are directly under the control of management is assessed by capital providers and impounded into a firm’s capital costs. Absolute efficiency (ROA) which is estimated as sales divided by total assets is not. Our results suggest that simple accounting ratios used in the accounting literature are not considered as informative to explain borrowing costs compared to relative efficiency that captures managerial operational performance.

Development and characterization of a mobile γ spectrometer and its field deployment for in situ radioactivity measurements

A mobile γ–ray spectrometer (AMESOS) has been developed using a 3”×3” NaI(Tl) detector, a custom–made mounting holder, and portable electronics to perform in situ measurements of radioactivity. The spectrometer was calibrated using standard point sources and its absolute efficiency was determined. As a field test operation, AMESOS was deployed on the premises of the University of Athens Zografou campus focusing on estimating the NORM levels. Data were analyzed and used to create radiological maps for the metropolitan UoA campus for the first time. Besides natural radioactivity levels, trace concentrations of 137Cs were also detected, attributed to the Chernobyl fallout in Greece. An overall steady performance of the spectrometer was observed throughout the field operation. AMESOS is ready to be deployed for in situ studies of environmental radioactivity and radwaste management.

Characterization of Plasmonic Scattering, Luminescent Down-Shifting, and Metal-Enhanced Fluorescence and Applications on Silicon Solar Cells

This paper studied characterized the plasmonic effects of silver nanoparticles (Ag-NPs), the luminescent down-shifting of Eu-doped phosphor particles, and the metal-enhanced fluorescence (MEF) achieved by combining the two processes to enhance the conversion efficiency of silicon solar cells. We obtained measurements of photoluminescence (PL) and external quantum efficiency (EQE) at room temperature to determine whether the fluorescence emissions intensity of Eu-doped phosphor was enhanced or quenched by excitation induced via surface plasmon resonance (SPR). Overall, fluorescence intensity was enhanced when the fluorescence emission band was strongly coupled to the SPR band of Ag-NPs and the two particles were separated by a suitable distance. We observed a 1.125× increase in PL fluorescence intensity at a wavelength of 514 nm and a 7.05% improvement in EQE (from 57.96% to 62.05%) attributable to MEF effects. The combined effects led to a 26.02% increase in conversion efficiency (from 10.23% to 12.89%) in the cell with spacer/NPs/SOG-phosphors and a 22.09% increase (from 10.23% to 12.48%) in the cell with spacer/SOG-phosphors, compared to the bare solar cell. This corresponds to an impressive 0.85% increase in absolute efficiency (from 12.04% to 12.89%), compared to the cell with only spacer/SOG.

Etiology and pathogenesis of acute pyelonephritis in children

Introduction. Acute pyelonephritis in children takes a leading place among the reasons for hospitalization. Objective. To study the epidemiological, anamnestic, diagnostic and clinical features of the course of pyelonephritis in children. Materials and methods. We have carried out a retrospective study of case histories of 142 children admitted to the urology department of the Emergency hospital №2 (Tomsk) with a diagnosis of acute pyelonephritis. Results. According to the results of our study, children of both sexes of young age (up to 1 year оf age) suffer from acute complicated pyelonephritis, whereas acute uncomplicated pyelonephritis is typical for girls over 3 years old. The sensitivity of ultrasound examination of the kidneys in acute pyelonephritis was 76.8%. The vast majority (96,8%) of acute uncomplicated pyelonephritis were caused by Escherichia coli. Escherichia coli was the cause of acute complicated pyelonephrities only in 30.8% of patients, Pseudomonas aeruginosa was ranked in second in frequency (15.4%), and Enteroccoccus faecalis was ranked third (11.5%). The following antibiotics retained their effectiveness among all the identified causative flora of uncomplicated pyelonephritis: fosfomycin, furagin, gentamicin, amikacin. Only amikacin showed absolute efficiency (100%) in the group of complicated pyelonephritis. 90% of bacteria showed sensitivity to fosfomycin, and 88.5% to cefepime and ertapenem. For children with acute pyelonephritis, the acute phase process of cytomegalovirus, Ebstein-Barr viral infections, previous herpes simplex virus infection, as well as contact with Chlamydia trachomatis, Ureaplasma urealуticum and Mycoplasma hominis are specific. Conclusion. The results of the study indicate the dynamics in the etiology and pathogenesis of acute pyelonephritis in children and a need for an annual monitoring in order to correct therapy.

ABOUT THE FEATURES OF FORMING THE PERFORMANCE OF SMALL AND MEDIUM ENTERPRISES

The authors conducted a sectoral measuring the performance of SMEs sample of the Odessa region for 2013-2019. The study found that all absolute and relative performance indicators increased. However, given the inflation rate for the period under review, the real level of absolute value-added decreased. The growth of absolute efficiency, i.e. the share of value-added in the price of goods and services SMEs was low (by 4.1%), but against the background of the crisis in the economy, this fact is positive and indicates an improvement in the ability of SMEs to create value-added. It was also found that during the studied period in the sectoral structure of performance of SMEs there were significant changes, which were manifested, in particular, in the change of leaders from transport, warehousing, postal and courier activities in 2013 to financial and insurance activities in 2019. Increase in performance for the entire sample in 2019 was due to two industries - financial and insurance activities and the processing industry. In addition, during the study period there was a reduction in the spread of performance scopes, i.e. equalization of performance within each industry. The authors found a certain paradox, which is that the increase in the labor productivity at SMEs leads to a reduction in the value-added of products (services) they produce. This paradox is called by the authors as "opposite effect", which is a phenomenon of atypical influence of individual components on the business performance. Moreover, it was reinforced by the atypical link between salaries and labor productivity, which appeared in 2019, and shows that wage growth not only does not stimulate an increase in labor productivity, but, on the contrary, leads to its reduction with a high degree of probability. Hence, the industries in which SMEs paid employees the highest salaries in 2019 had the lowest level of labor productivity and, conversely, the industries with the lowest salaries had the highest labor productivity among other industries studied. Thus, the features of the forming the performance of SMEs are the identified general trends in its dynamics, structural changes and a certain paradox, which is the atypical impact of labor and salary on performance and productivity in this sector of Ukraine's economy.